The pps timestamp initialization was accidentally lost on vlv/chv in
 commit 
a4a5d2f8a96e09844a91469e889f15bd5e927399
 Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
 Date:   Thu Sep 4 14:54:20 2014 +0300
    drm/i915: Track which port is using which pipe's power sequencer
Restore it so that we avoid introducing random delays into the pps operations
during/after driver init time.
Cc: Imre Deak <imre.deak@intel.com>
Reported-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
 
        if (is_edp(intel_dp)) {
                pps_lock(intel_dp);
-               if (IS_VALLEYVIEW(dev)) {
+               intel_dp_init_panel_power_timestamps(intel_dp);
+               if (IS_VALLEYVIEW(dev))
                        vlv_initial_power_sequencer_setup(intel_dp);
-               } else {
-                       intel_dp_init_panel_power_timestamps(intel_dp);
+               else
                        intel_dp_init_panel_power_sequencer(dev, intel_dp);
-               }
                pps_unlock(intel_dp);
        }